The invention relates to a microendoscope with a distal probe tip, which has, in particular, a diameter of up to approximately 1 mm and which houses an optical subassembly at least provided with a micro-objective and an image-transmitting element, with an image-transmitting system being connected to the optical subassembly.
In microendoscopy, for working diameters below 1 mm, flexible endoscopes are known, which have close to the distal end a lightweight handle, whose rigid tip can extend, for example, over a length of 30-120 mm. The microendoscope tip generally has the following structure:
In the center at the distal end there is a micro-objective, formed from one or more micro-lenses, e.g., with an outer diameter of 0.5 mm. This distal micro-objective is usually placed directly on a subsequent image guide with the same active diameter. At the proximal end, the pixel-structured image transmitted by the image guide is prepared by an objective for visual observation or for projection on a video-camera array.
Optical fibers, which are fastened mechanically close to the proximal end and which are connected to a light source via a connecting light guide, are arranged around the distal micro-objective and the image guide along the probe length for illuminating the image field. In the region of the distal tip, micro-objectives, image guides, and optical fibers are installed in a rigid or semi-flexible tube, which forms a holder and guide for these components.
The light-transmitting and image-transmitting elements are usually fastened in a flexible protective sleeve from the handle outwards to the proximal end. For certain applications, an empty channel, represented, for example, by a micro-lumen sleeve or a metal tube, can also be integrated into the probe.
Many microendoscopic applications in medical technology and for industrial applications require small working diameters starting at 0.15 up to about 1 mm. These working diameters permit only about 3000 pixels for the image guide due to space requirements; however, the applications demand higher resolutions with more than at least 10,000 pixels (e.g., 20,000, 30,000, 50,000). In addition, the handle of the microendoscopic probe and the probe feed line should be configured as lightweight as possible, which requires the image-transmitting system to have a flexible image-guiding system to the endoscopic camera (for video observation). Image guides with pixel counts greater than 3000 do not allow distal probe tips with working diameters of less than 0.5 mm for the structure described above.